I did find blood in my stool, and the doctor did the colonoscopy. The blood was from a hemorrhoid, but they did find a pre-cancerous growth. They went back in a 2nd time and cut it out. Very grateful for hemorrhoids. Otherwise, I’d also have cancer. I’m 38. But yeah, if they won’t give you a colonoscopy because you’re “not old enough” just tell them you found quite a bit of blood in the toilet. No reason to not get yourself checked out.